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Three aspects in determining the first natural frequency of steel joist supported floors were studied. The aspects are: 1) determining which finite element model best predict the behavior of joist-slab tee-beams, 2) investigating the ability of proposed equations to calculate the effective moment of inertia of joist-slab tee-beams, and 3) developing a finite element model to predict the first natural frequency of steel joist supported floors. Several finite element models were tested to determine which one best predicted the experimental results of six joist-slab setups. The model which best predicted the experimental results was used. Next, a study was done to determine the ability of a proposed equation to predict the effective moment of inertia of joist-slab tee-beams. The study modeled and analyzed 130 joist-slab configurations and compared the results to those calculated using the proposed equations. Finally, a finite element modeling technique was developed to predict the first natural frequency of steel joist supported floors. Seven in-situ floors were experimentally tested, and those results were compared to the predicted values given by the models. / Master of Science

Iron Oxide Nanoparticles (IONPs) are a multifunctional nano-material that allows for MRI imaging, intravenous-controlled drug movement, and hyperthermia. The objective of this study is to optimize and control IONP hyperthermia and cope with aggregation using Finite Element (FE) Modeling and statistical physics. The FE model is first used to demonstrate the advantages of changing IONP heat dissipation in time, which can increase energy density inside tumors while decreasing the energy delivered in healthy tissue. Here, this is defined as target-specificity. Second, this model is used to demonstrate that time-dependent IONP heat dissipation allows for control of temperature distributions inside the body. Third, the FE model is used to solve the temperature distributions resulting from capillary diffusion of IONPs. This study shows that capillary diffusion combined with direct injection results in improved homogeneity of temperature distributions. Fourth, using a square-difference scheme, non-time domain parameters including the number of IONP injections, the location of injections, IONP distribution width, and heating intensity are optimized to improve target-specificity and temperature homogeneity. Collectively, this study contributes to hyperthermia by optimizing time- and non-time- domain parameters, controlling hyperthermia, and quantifying aggregation with a new theory. / Master of Science

In my dissertation, I developed mixed hp-finite element methods for linear elasticity with weakly imposed symmetry, which is based on Arnold-Falk-Winther's stable mixed finite elements. I have proved the h-stability of my method for meshes with arbitrary variable orders. In order to show the h-stability, I need an upper limit of the highest order of meshes, which can be an arbitrary nonnegative integer. / text

Over the last 20-30 years the subject of spin in tennis has become increasingly important. A great deal of work has been done to establish the effects which, increased levels of spin have, on shots. The most prominent effect of increased spin in a tennis shot is the resulting deviation in flight which allows players to, amongst other things, strike the ball harder with top-spin in the knowledge that it will still fall inside the court due to the extra aerodynamic downward force. With such significant advantages available racket manufacturers are naturally keen to maximise spin generation. That being said, very little research has been performed into the subject of spin generation in tennis and the affecting factors. This thesis details the development of a finite element model which is to be used to allow a greater understanding of spin generation and how varying properties such as string density (the number of strings in a string-bed), gauge and orientation affect its magnitude. The primary aim, or goal, of this research is to create an FE model which can be used to model oblique impacts and measure the resulting spin. Whilst considerable focus was placed on developing novel, modelling techniques to create the FE model, a great deal of emphasis was also placed on its validation. The validity of the model was examined under static loading conditions, such as that experienced during stringing. The dynamic performance was also validated using a combination of modal analysis and high speed video of dynamic impacts. Each of the validation methods provided assurance of the models performance, with all error margins less than 5%. The two areas of the FE model which required the most attention were the interaction properties (specifically coefficient of friction (COF)) and material properties. Previous studies have sought to obtain a single value for the COF of a tennis racket/ball system but this study examines how the COF varies as the strings interact first, with themselves and secondly with the ball. Each of the validation methods (dynamic and static) were deemed successful as they provided concise data which could be readily compared with the results produced by the FE model. Having validated the model s performance, with respect to predicting outbound spin, a number of oblique impact angles were modelled to allow a greater understanding of how the mechanisms of spin generation change with the inbound trajectory of the ball. This analysis showed that for the impact conditions studied the contact time of the impact was reduced from 6.2 milliseconds to 5.7 milliseconds when the angle was increased from 32 degrees to 40 degrees. Furthermore, a number of novel string-beds were modelled, with varying string orientations (between 30 degrees and 60 degrees relative to the rackets frame) and subjected to a similar analysis procedure, with their results providing the concluding section of the thesis.

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy